The present invention is related to a printed circuit board testing apparatus, and more particularly, to a printed circuit board testing apparatus of multi-layered printed circuit board in the planar transformer structure, which is applied to test the short circuit in the annular circuit.
In the early stage, a computer had a huge size. One computer was as huge as one room because the early computer was made by vacuum tubes, circuits, and transformers. Later, these components with huge sizes were replaced by the semiconductor and the printed circuit board (PCB). Now, thanks to the printed circuit board, the computer has a small size that can be carried with one. This product, the printed circuit board is to be used, not only in a motherboard, but also in a interface card in a computer or other household appliances. The printed circuit board has made the complex circuit and copper wire between each components through etching on a board by a meticulous and ordered scheme. The components will interact with each other as long as being plugged the components in the board.
Therefore, one printed circuit board is often a xe2x80x9csandwichxe2x80x9d with several layers of circuits. For example, a planar transformer has four layers at least and presently seven layers at most. The more layers it has, the smaller space it occupies and the fewer noisy signal of circuit it has. However, due to these circuits are formed through etching directly on the printed circuit board, if the etching is not complete, the circuit of the printed circuit board might be cut off and generate a phenomenon of short circuit.
In order to control the producing quality effectively, it is necessary to test whether there is a short circuit formed in the circuit of the printed circuit board after the etching process of a printed circuit board is complete. Please refer to FIG. 1. FIG. 1 is a schematic view showing the short circuit testing of the printed circuit board 11 in a planar transformer according to the prior art. Due to the fact that the planar transformer produces a change of inductance value by the mutual inductance effect between the coil and the magnetic field, the upper surface and the lower surface of the coil 13 of the printed circuit board are clipped by two magnetic elements 121 and 122 respectively before the performing of the short circuit testing of the printed circuit board 11 in a planar transformer. The mutual inductance effect is produced by the interaction between the two magnetic elements 121 and 122 and the coil 13 of the printed circuit board 11. Then, the LCR minimeter 14 is connected to two terminal points 151 and 152 of the coil 13 to measure whether the inductance value is the predetermined inductance value. If the measured inductance value is not the predetermined value, it means that the short circuit is formed in the circuit of the printed circuit board in the planar transformer. However, the common way of testing uses one single meter and merely measures the printed circuit board in one planar transformer at a time, which does not conform to the economic benefits in the market of mass production today. Furthermore, it is necessary to clip the upper surface and the lower surface of the printed circuit board with magnetic elements in advance before the testing process. This step not only wastes the time and the energy, but also wears and tears the components and damages the printed circuit board easily when pulling the magnetic element out and plugging the magnetic element in. In that way, the cost is increased unnecessarily.
In order to overcome the foresaid drawbacks, the present invention provides a printed circuit board testing apparatus of multi-layered printed circuit board in the planar transformer structure for testing the short circuit in the printed circuit board.
It is an object of the present invention to provide a printed circuit board testing apparatus for testing whether there is a short circuit formed in the circuit of the printed circuit board.
It is another object of the present invention to provide a printed circuit board testing apparatus for being used to test the short circuit in an induction element of a printed circuit board, including: a signal generating device, an inducing device, a signal converting device, a signal processing device, and a warning device. The signal generating device is used for providing a first signal. The inducing device is electrically connected to the signal generating device for performing a mutual inductance effect with the induction element of the printed circuit board and making the first signal to produce a second signal in response to the mutual inductance effect. The signal converting device is electrically connected to the inducing device for converting the second signal into a direct current signal and obtaining a peak value voltage from the direct current signal. The signal processing device is electrically connected to the signal converting device for outputting a controlling signal according to the relationship between the peak value voltage and a reference voltage. The warning device is electrically connected to the signal processing device and driven by the controlling signal for changing the status thereof and generating a warning signal in response to the status change of the controlling signal when a relative voltage standard obtained by the signal processing device is not identical to a predetermined voltage standard due to the short circuit of the induction element of the printed circuit board, thereby judging whether there is a short circuit formed in the induction element of the printed circuit board.
In accordance with the present invention, the signal generating device is an oscillator.
Preferably, the inducing device is an inductor.
Preferably, the signal converting device is a rectifier.
Preferably, the reference voltage is provided by a power supply.
Preferably, the signal processing device includes a comparator and a voltage detecting device. The comparator is electrically connected to the signal converting device for comparing the peak value voltage and the reference voltage and outputting the relative voltage standard. The voltage detecting device is electrically connected to the comparator for detecting whether the relative voltage standard is the predetermined voltage standard and outputting the controlling signal.
Preferably, the warning device is a light-emitting diode.
Certainly, the warning device can alternatively be a buzzer.
Preferably, the induction element is a transformer disposed in the printed circuit board.
It is another object of the present invention to provide a printed circuit board testing apparatus for being used to test the short circuit in an induction element of a printed circuit board, including: a signal generating device, an inducing device, and a comparator device. The signal generating device is used for providing a first signal. The inducing device is electrically connected to the signal generating device for performing a mutual inductance effect with the induction element of the printed circuit board and making first signal to produce a second signal in response to the mutual inductance effect. The comparator device is electrically connected to the inducing device for comparing a peak value voltage and a reference voltage in response to the relationship between the peak value voltage and the reference voltage, thereby judging whether there is a short circuit formed in the induction element of the printed circuit board.
In accordance with the present invention, the signal generating device is an oscillator.
Preferably, the inducing device is an inductor.
Preferably, the reference voltage is provided by a power supply.
Preferably, the comparator device includes a signal converting device, a comparator, and a voltage judging device. The comparator device is electrically connected to the inducing device for converting the second signal into a direct current signal and providing the peak value voltage. The comparator is electrically connected to the signal converting device for comparing the peak value voltage and the reference voltage in response to the comparative value of the peak value voltage and the reference voltage, thereby outputting a relative voltage standard. The voltage judging device is electrically connected to the comparator for judging whether the relative voltage standard signal is identical to a predetermined voltage standard, thereby outputting a controlling signal.
Preferably, the signal converting device is a rectifier.
Preferably, the voltage judging device is further electrically connected to a warning device and driven by the controlling signal for changing the status thereof and generating a warning signal in response to the status change of the controlling signal when a relative voltage standard obtained by the signal processing device is not identical to a predetermined voltage standard due to the short circuit of the induction element of the printed circuit board.
Preferably, the warning device is a light-emitting diode.
The foregoing and other features and advantages of the present invention will be more clearly understood through the following descriptions with reference to the drawings, wherein: